Innocent murmurs and normal paediatric cardiovascular variants — formative SAQs

SAQ 1 (10)

A thriving 4-year-old is referred to the general paediatric clinic because a "heart murmur" was heard at a preschool check. The child feeds, plays and grows normally. On examination there is a soft, short, vibratory systolic murmur at the lower left sternal edge that softens when the child sits up; heart sounds, femoral pulses and oxygen saturation are normal. [1] [3]

1. Give your clinical diagnosis and the reasoning. (3) [3]
2. List five auscultatory or clinical red flags that would force you to abandon that diagnosis. (4)
3. Outline your management and safety-net advice to the family. (3)

Model answer

Diagnosis (3): This is a Still's vibratory murmur — the commonest innocent murmur of children aged 2–7 years: soft, short, vibratory/musical, lower left sternal edge, softer when upright, with normal heart sounds, normal femoral pulses and normal saturation in a thriving asymptomatic child. [3] [1]

Red flags that exclude the label (4): any diastolic, holosystolic or continuous murmur (other than a venous hum); a harsh, grade ≥3/6 murmur or one with a thrill; a fixed or widely split S2, single or loud P2; abnormal femoral pulses or radio-femoral delay; symptoms (failure to thrive, exertional intolerance, syncope, cyanosis); or a murmur radiating to the back or neck. A neonatal murmur should not be labelled innocent on first hearing. [1] [2]

Management and safety-net (3): Make the diagnosis clinically — no echocardiogram, ECG or CXR is indicated. Reassure the family that the heart is structurally normal, allow full activity with no restriction, give no endocarditis prophylaxis and arrange routine dental care. Document the specific innocent murmur and the reasoning. Safety-net to return if new symptoms appear (exertional symptoms, syncope, breathlessness, colour change, poor growth). [1] [3]

SAQ 2 (10)

A 6-week-old infant is found to have a soft systolic murmur at a routine check. The baby is feeding and growing well and is pink in room air. [1] [2]

1. How does your approach to a neonatal/young-infant murmur differ from the 4-year-old above, and why? (5) [1]
2. Justify the role (or not) of pulse oximetry and echocardiography in this infant, with reasoning. (5)

Model answer

Different approach (5): Apply a much lower threshold and do not label a newborn or young-infant murmur innocent on first hearing. Neonatal murmurs carry a higher probability of structural disease than the same murmur in an older child, the transitional circulation changes the auscultatory picture, and ductal-dependent lesions can present after discharge. Refer to paediatric cardiology rather than reassuring. [1] [2]

Investigations (5): Measure an oxygen saturation in room air — a low or differential saturation can flag critical congenital heart disease that auscultation misses, and pulse oximetry screening is part of newborn assessment. [1] In a neonate/young infant with a murmur, arrange echocardiography via paediatric cardiology because the pre-test probability of pathology is higher and the clinical picture is less reliable. Reserve the "no investigation" pathway for the older child who clearly meets all innocent criteria. [1] [5]